Developer interest in OS X Yosemite appears to be about four times that of 2013's Mavericks, online advertising network Chitika concluded today.

Chitika mined its data from June 2 to July 3, and found that Macs running Yosemite showed in its logs several times more frequently than did last year's Mavericks at the same time in its post-unveiling timeline.

Apple introduced Yosemite, which also goes by the more mundane name of OS X 10.10, on June 2 at its annual developers conference. That same day, the Cupertino, Calif. company offered a preview. Only Apple registered developers are to have Yosemite at this point; they must pay $99 annually for a membership and access to pre-release code.

Within the first three days after the conference keynote, Yosemite accounted for 0.15% of all U.S. and Canadian Mac traffic on the Chitika ad network. The 0.15% would represent 15 out of every 10,000 Macs. At the same point last year, Mavericks had accounted for about 0.01% of all Mac traffic.

Thirty days after Yosemite's availability to developers, its share was 0.20% -- 20 out of every 10,000 systems -- or four times that of Mavericks' 0.05%.

Chitika rationalized the increase use of Yosemite by pointing out that the upgrade features "prominent changes," including a partial visual overhaul, a revamped Safari browser, and "Continuity," an umbrella term for several new features that link iPhones and iPads to Macs.

Other Web analytics firms have yet to record usage or user share data for Yosemite. That's not surprising: Last year, Net Applications did not post numbers for OS X Mavericks until September, the month before its public launch.

Apple has not said exactly when it will ship Yosemite, but has pegged the delivery date as some time in the fall. If the company follows 2013's schedule, it will release OS X Yosemite on Oct. 21.

Before that, Yosemite's share of Mac traffic -- whether measured by Chitika or others -- will undoubtedly be much larger than Mavericks in the weeks before its launch, as Apple has promised to issue a public beta of Yosemite this summer.

Yosemite's public preview will be Apple's first for OS X in 14 years.

Apple has said it will accept up to one million participants in the public beta program; as of Wednesday, it was still taking applications, indicating that it had not exhausted the million-person pool.

Mavericks accounted for 59% of all Macs that went online in June, according to Net Applications. The operating system will probably peak at around 70% in September before users start snatching the free Yosemite to upgrade their Macs.